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EPA Home > Region 5 > Air > Correspondence


August 17, 1998

Mr. Bharat Mathur
Chief, Bureau of Air
Illinois Environmental Protection Agency
1021 North Grand Avenue East
P.O. Box 19276
Springfield, Illinois 62794-9276

Dear Mr. Mathur:

Thank you for your timely submittal of the PM 2.5 Monitoring Network Design for Illinois. As you know, the deployment of a PM 2.5 monitoring network is a critical component in the implementation of the PM 2.5 National Ambient Air Quality Standard. The ambient data from this network will drive an array of regulatory decisions, ranging from designating areas as attainment or nonattainment, to developing cost-effective control programs, and tracking the progress of such programs.

Thank you for your commitment to establish 45 PM 2.5 monitoring sites in Illinois by the end of Calendar Year 1999. I am pleased that of these, you intend to deploy 26 sites by the end of Calendar Year 1998. This is in accordance with the timetable for monitor deployment set up by the Office of Air Quality Planning and Standards (OAQPS).

I would also like to commend you for your early PM 2.5 monitoring efforts in deploying nine dichotomous samplers in the Chicago and East St. Louis areas and submitting these data to the Aerometric Information Retrieval System (AIRS). The experience you have gained, as well as the data you have collected will be invaluable to OAQPS in early characterization of the national fine particulate concentrations.

There are several sites in your network at which you plan to sample on a once in six day schedule. You have indicated that all of these sites are Special Purpose Monitoring Sites (SPM).

These sites are located at:
Champaign County (AIRS #171900004),
Although the minimum sampling frequency for all State and Local Air Monitoring Stations (SLAMS) is once every third day, an SPM may sample according to any operating schedule. As these sites are predominantly population oriented or background sites, I would prefer that these sites be SLAMS. As there is no available guidance for granting a waiver for a SLAMS to operate with a decreased sampling frequency, however, I will approve these sites to operate as SPM for one calendar year. These sites should be operated following all the guidelines for SLAMS except for sample frequency. By the time the first annual network review is conducted, additional guidance on sampling frequency may be available. This will permit the Region to evaluate sampling frequency for current or planned SLAMS and grant waivers for decreased sampling frequency based on recorded PM 2.5 data.

I am pleased that more than one third of your proposed PM 2.5 sites will be collocated with ozone monitors, and that several of your proposed PM 2.5 sites will be collocated with meteorologic monitoring. I am confident that ultimately these data will prove to be useful in establishing control strategies for both PM 2.5 and ozone.

As there are little historical PM 2.5 monitoring data available, this design represents a very good first attempt at what will be a dynamic process. As data are collected and as newer monitoring technologies become available, it may be useful or necessary to redefine the network so that it continues to provide information essential to describe ambient PM 2.5 concentrations as well as to assist in developing control strategies for PM 2.5. In addition, budget constraints and changes in implementation goals arising from the Agency’s response to the National Academy of Science’s review of the PM 2.5 National Ambient Air Quality Standard monitoring program may lead to reevaluation of monitoring strategies and ultimately to changes in network design.

I am pleased to conditionally approve your PM 2.5 monitoring network pending Regional site evaluations and approval of the FY 99 budget. I am looking forward to receiving your annual revised PM 2.5 monitoring network description by July 1, 1999, as required by 40 CFR 58.26.

I appreciate your continued high level of commitment to the coordination of the PM 2.5 monitoring program in Illinois. I consider the implementation of the PM 2.5 network, as I’m sure you do, to be a critical priority.

If you have any questions or comments, please feel free to contact me or have your staff contact Maryann Suero, of my staff, at (312) 886-9077.



Stephen Rothblatt, Acting Director
Air and Radiation Division

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This Information Last Modified On: 09/18/2008 03:58 PM